The present invention relates to buckle folders for folding sheets of paper and more particularly to buckle folder plates.
Typical buckle folders are designed to accept single documents or sheets to be folded. Accordingly, the dimension of the paper gap between the buckle or fold plates is designed in relation to the anticipated general paper thickness.
Depending on the number of fold plates or buckle plates employed, the first fold plate usually has the smallest gap with subsequent fold plates progressively increasing the gap between the plates because of the increased paper thickness due to the progression of the folds.
In recent years, folders of the buckle plate design have been employed as part of automated mail processing systems wherein continuous forms or cutsheet documents are singulated, optically read for group or address association, accumulated by address definition and folded as a set. The term for this kind of folding is "nestfolding".
The nestfolded document package is then transferred to an inserting system for adding additional inserts and ultimate enveloping and franking, etc.
When processing individual documents, the paper thickness increases, depending upon the fold characteristic, is very predictable and can therefore be fixed for all fold plates employed within a particular system. However, when the number of documents to be sent to a folder vary between approximately 1 and 15 pages, for example, the space accommodation within the fold plates needs to account for this variance in thickness.
The basic design criteriae for buckle fold plates has the distance between the fold plates usually kept as small as convenient in order to permit the easy movement of the paper between these plates. However, at the same time the distance between the fold plates should be as tight as possible in order to prevent the paper from bowing out or crumpling when the leading edge of the paper reaches the buckle plate paper stop and the continuously running folder rollers are creating the buckle for the fold. The wider the gap within the foldplate, the less accurate is the fold performance.
Fixed gap buckle plates in buckle folders are fixed for a certain number of sheets. If it is desired to feed and fold one sheet and thereafter three sheets the buckle plates must be adjusted in order to accommodate the increased thickness. This requires shutting down the operation and adjusting the gap between the buckle plates. When a different thickness of sheets is to be folded, the gap between the buckle plates must again be adjusted. This results not only in time consuming operations but expensive interruptions in the flow of the sheets being folded.